1. Field of the Invention
The present invention relates generally to an industrial endoscope and, more particularly, to an arc-shaped flexible printed circuit film type endoscope using an imaging device with driving holes, in which the driving holes are formed at regular intervals in a longitudinal direction in the endoscope having a flexible printed circuit film connected to a head housing accommodating a charge coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) sensor as the imaging device, and interact with a driving device having a toothed part such as an intermittent gear or sprocket, thus allowing the endoscope to be precisely driven.
2. Description of the Related Art
Generally, a plurality of heat transfer tubes is mounted on the tube sheet of a secondary side of a steam generator installed in a nuclear power plant, with very narrow gaps formed between the heat transfer tubes. Here, sludge or impurities may enter the gaps between the heat transfer tubes, thus causing damage to the heat transfer tubes.
Therefore, in order to prevent the heat transfer tubes from being damaged by the sludge or impurities, visual inspection is periodically conducted. The visual inspection is performed through endoscopy using an endoscope camera which is mounted to a micro robot or the like.
Endoscopy is the non-destructive inspection method of visually inspecting the interior of a human body organ or an object without impairing the human body organ or the object, by inserting an insertion tube into the human body organ or the object.
Endoscopes are typically classified into medical and industrial endoscopes according to the object to be inspected. Among them, the manufacture of the industrial endoscope is difficult because its insertion part is small and thin.
Thus, in Korea, the industrial endoscope has not been researched and developed nor has it come onto the market yet. The supply of most endoscopes depends on imports.
The industrial endoscope includes an input-output unit for visually inspecting an object, a light source, and an insertion tube. Since most inspection instruments are too large to be inspected by an inspector, a lot of time, labor and expense are required.
Further, the industrial endoscope adopts an analogue method. Thus, in order to store photographed images, photographs must be printed through chemical treatment, and the inspected result must be read via image equipment which is installed in an inspection site, so that there are restrictions of time and space. Further, since it is impossible to transmit data of the inspected result over a network, it is impossible share the data in real time.
In consideration of these aspects, as the conventional industrial endoscope which has been used to visually inspect the heat transfer tubes, an endoscope which has an industrial endoscope camera (including an endoscope camera and a CCD sensor) and a belt or a chain having a cable therein has been proposed.
The conventional endoscope is problematic in that the chain or belt is thick, so that it occupies a large space when rolled into a circular shape, and therefore it is difficult to mount the endoscope to a small space such as a robot so as to inspect the interior of a narrow heat transfer tube.
Further, the conventional belt- or circular cable-type endoscope camera is problematic in that when it is constructed to be very thin, it is too flexible, so that it is difficult to maintain strength when linearly extended. Further, the endoscope camera, the cable, an illumination part and other parts are integrally installed in the chain- or belt-type feeding means, so that a bending radius is large. Thus, it is difficult to mount the conventional endoscope to a narrow space such as a robot and to handle it.
Meanwhile, in order to photograph a small space, there has been proposed Japanese Patent Laid-Open Publication No. 2006-319401, which is entitled “Remote Inspection System”.
The remote inspection system includes a CMOS image sensor as an imaging device of a video camera. By manipulating a power supply for a video camera and a white LED which is connected in a conduction state through a flexible spiral metal tube to an inspection head having the white LED for illumination, the remote inspection system photographs a narrow space.
Thus, a photographing unit includes the CMOS sensor and the illumination part, so that it is possible to photograph and inspect a small space. However, since a circuit means or a transmission means for processing or transmitting a photographed image cannot be formed on the spiral metal tube itself, the circuit means or the transmission means for processing or transmitting the photographed image must be provided separately from the spiral metal tube, thus inconveniencing a manufacturer.
In order to solve the problems occurring in the conventional industrial endoscope, Korean Patent Appln No. 10-2008-79894 was filed on Aug. 14, 2008 by the inventor of the present invention and is entitled “Arc-shaped flexible printed circuit film type endoscope using imaging device”.
As shown in FIGS. 1 to 3, the arc-shaped flexible printed circuit film type endoscope using the imaging device according to the cited document includes an image photographing means 10 and an object insertion means 20. The image photographing means 10 includes a head housing 13 to which an imaging device 11 having a lens 11a and an illumination means 12 are mounted, and photographs an image. The object insertion means 20 includes an arc-shaped flexible thin foil 21, an insulating adhesive film 22, a circuit film 23 and an insulating protective film 24 which are layered and inserted into the interior of an object which is to be inspected. The object insertion means 20 is connected at one end thereof to the image photographing means 10 and connected at the other end to a transmission cable 26 through a connector 25. The illumination means 12 comprises LED lamps, and is configured so that lamp supports 12b are inserted into corresponding support insertion grooves 13b of the head housing 13 in such a way that each LED lamp 12a mounted to the corresponding lamp support 12b is inserted into a corresponding lamp insertion hole 13a of the head housing 13, and thereby an LED terminal contact point formed on the back of each lamp support 12b is in contact with a terminal contact point formed on a side surface of the rear portion of the corresponding support insertion groove 13b. Further, the head housing 13 includes a plurality of lamp insertion holes 13a which are formed in the upper and lower portions of the front end of the head housing 13. The plurality of support insertion grooves 13b is formed in the head housing 13 to communicate with the lamp insertion holes 13a. A window 13c is formed in the central portion of the front end of the head housing 13. An imaging device insertion hole 13d is formed in the middle portion of the head housing 13 in a longitudinal direction thereof to communicate with the window 13c. A terminal contact point of the imaging device 11 is formed on a side surface on the rear portion of the imaging device insertion hole 13d. A connection surface 13e is provided on the rear end of the head housing 13. Pin holes 13f are formed in an end of the connection surface 13e. The image photographing means 10 and the object insertion means 20 are connected to each other via a locking part 14 and locking pins 15.
However, as shown in FIG. 4, the endoscope according to Korean Patent Appln. No. 10-2008-79894 constructed as described above is problematic in that the object insertion means 20 of the endoscope is driven between rollers 30 by frictional force acting between the rollers 30 which are rotated while being in close contact with each other, so that slippage may occur in a contact surface between the object insertion means 20 having the shape of a thin plate and the rollers 30, and thereby it is difficult to precisely control the driving of the endoscope.